Wireless system enables UAVs to communicate with operators

British engineers are preparing to test technology for sending data across an airborne network of civilian unmanned aerial vehicles (UAVs).

The wireless communication system is designed to allow a UAV to securely send video footage and other information to its ground-based operator at the highest possible speed, even when it is out of direct range.

It is the latest technology to emerge from the aerospace industry’s Autonomous Systems Technology Related Airborne Evaluation & Assessment (ASTRAEA) programme, alongside a device for sensing and avoiding vehicles in commercial airspace that is also undergoing testing.

‘If you have critical, time-sensitive data, there’s no point having it locked on the aircraft. You have to have a mechanism to get it to its intended end user,’ said project manager David Rees from defence company Cassidian, speaking at the ASTRAEA national conference on 7 September 2011.

‘We are capable, with the solution we’re developing, of utilising the best media for the data type, importance and urgency,’ he added.

The system can also use existing communications infrastructure and satellite communications, according to Rees. ‘We don’t have to have a simple end-to-end delivery from A to B. It could go over a number of bearers with different capabilities.’

One of the key challenges for the technology is managing the different links in the network as they are established, increase and decrease in strength and then disappear as the different craft move around.

The system has to decide which path to send the data by and alter it accordingly as the network changes. This could involve changing the type of data sent if higher speeds become unavailable.

For example, high-resolution video can be altered to low resolution and then to still images if a network connection loses strength, and back again as better links are re-established.

The other main difficulty was reducing the power, size and weight of the technology to make it suitable for small UAVs.

‘The capability we’ve developed today, we could probably plug into a Euro Hawk [a 3,850kg unmanned spy plane] tomorrow, but that’s a huge aircraft,’ said Rees.

‘If we want to evolve this technology to a point where it becomes viable for UAVs that have a maximum weight of 50kg or 20kg, then… the way we evolve and manage our communications capability is a critical part of that solution.’

The Cassidian team successfully tested varied data transfer between two nodes on a network earlier this year. The team is now preparing to test a second prototype, which is roughly the size of a small cereal box and uses 110W of power, in the first part of 2012.

Another technology being tested for the ASTRAEA programme is a sense-and-avoid system that uses a variety of visual and electromagnetic sensors to alert a UAV to oncoming craft, buildings and terrain, and to allow it to plot a course around them.

This involves two systems, one for immediate collision avoidance and another to keep the craft out of the path of other vehicles by making minor course adjustments well in advance of contact.

‘We want the system to behave like other aircraft,’ said BAE Systems’ Darren Ansell, technical manager on the ASTRAEA communications programme. ‘We don’t want it to be doing weird and wonderful manoeuvres; it’s got to behave and act like any other aircraft.

‘The system has to be compliant with rules of the air; it has to turn the right way; it has to do what other airspace users would expect a conventional aircraft to do in that kind of situation.’

ASTRAEA is a £62m industry-led consortium programme supported by the UK government to create the technologies, systems and regulations needed to operate civilian UAVs.